Optical fiber technology is currently revolutionizing the telecommunications industry. Over the past decade, tremendous advances have been made in the field and all indications show that even greater advances will be made in the future. For example, one prediction estimates that in the relatively near term, systems will exist which are capable of carrying 10 million conversations simultaneously on a single fiber. Optical fiber communication systems offer many advantages over past systems, such as systems using copper wire or radio frequency links as a transmission medium, including: lower transmission losses, higher bandwidths, higher transmission rates, lower implementation costs, and greater electrical isolation characteristics. Because of these and other advantages, great efforts are currently being made to develop and implement optical fiber communication systems and such systems will most likely dominate the telecommunications industry in the near future.
An important component in any communication system is the switch which the system uses to establish communication channels among two or more of its interfaces. In optical fiber communication systems this function can be performed by an optical fiber switch. An optical fiber switch is a switch which is capable of optically connecting, or aligning, any one of a first group of optical fibers with any one of a second group of optical fibers so that an optical signal can propagate through the spaced junction from one fiber to the other. Such a switch should operate very rapidly and should be capable of aligning the two fibers in such a way that very little signal power is lost at the transition between the fibers.
Optical fiber switches generally include fiber positioning means, alignment signal emitter means and computer control means interconnected thereto. A fiber positioning means is provided near the end of each fiber to selectively point the end of a given fiber in one fiber group toward the end of a given fiber in the other fiber group for switched optical transmission therebetween. An alignment signal emitter means is provided near the end of and in predetermined spaced relation to the end of each fiber to emit an alignment signal for receipt and use in controlling the fiber positioning means when aligning the ends of selected fibers in the fiber groups for switched optical transmission therebetween. See e.g., the inventor's prior U.S. Pat. Nos. 4,512,036 and 5,177,348.
As optical fiber communication systems are developed to service larger numbers of customers, larger optical fiber switches will be necessary to accommodate switching between larger groups of fibers. Correspondingly, increased fiber alignment speeds and switch serviceability, as well as decreased signal power loss and overall switch complexity will be highly desirable. In this regard, current optical switch designs present limitations. For example, in one currently employed design, all of the alignment signal emitter means for a fiber group are mounted on a common support, thereby presenting a serviceability problem should any one of the alignment signal emitter means fail, and further making it increasingly difficult to achieve predetermined positioning of the alignment emitter signal means relative to corresponding fiber ends as the number of fibers in fiber groups increases. Deviations from the desired predetermined relative positioning can result in signal power losses across a switch junction. Additionally, the control means of current switches are pre-programmed with specific positional information for each potential fiber interconnection combination for use in controlling the fiber positioning means, thereby presenting computer pre-programming complexities and increased delays in processing as the number of fibers in fiber groups increases.